https://en.wikipedia.org/wiki/Indonesian_rupiah

However, although it is a currency symbol, it doesn’t appear to be a glyph, at least in Unicode (http://unicode.org/charts/PDF/U20A0.pdf). It’s just written using two letters.

Many thanks. It is a glyph in my Centaur MT where it has private use area unicode F6DD

Some good answers here:

http://typophile.com/node/16012

Thanks Joshua for resurfacing such an interesting thread!
By the way, I think Rp could be made a nice ligature…